I agree that I wouldn't want to waste the money or my hopes on an IUI if I thought I already O'd, I would rather wait until next month...Personally I have used the answer tests and didn't like them, they were very hard to read, I got a bunch of what I thought were positives or close to it, and then finally got a positive that was a glaring difference, very confusing. They are cheaper, but I think that if I was doing something like IUI and needed to be absolutly positive I would get one of the OPK kits with the

that way there is no line comparing, just a

for a yes.